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[RFC,2/2] Btrfs: make a source length of 0 imply EOF for dedupe

Message ID 42687716155fb892c55b56f22a995b39e543f906.1479427384.git.osandov@fb.com (mailing list archive)
State New, archived
Headers show

Commit Message

Omar Sandoval Nov. 18, 2016, 12:07 a.m. UTC
From: Omar Sandoval <osandov@fb.com>

This makes us consistent with both reflink and the XFS implementation of
dedupe.

Signed-off-by: Omar Sandoval <osandov@fb.com>
---
 fs/btrfs/ioctl.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)
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Patch

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index e23f945..320fb35 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -3121,21 +3121,25 @@  static int extent_same_check_offsets(struct inode *inode, u64 off, u64 *plen,
 static int btrfs_extent_same(struct inode *src, u64 loff, u64 olen,
 			     struct inode *dst, u64 dst_loff)
 {
-	int ret;
-	u64 len = olen;
+	int ret = 0;
+	u64 len;
 	struct cmp_pages cmp;
 	bool same_inode = (src == dst);
 	u64 same_lock_start = 0;
 	u64 same_lock_len = 0;
 
-	if (len == 0)
-		return 0;
-
 	if (same_inode)
 		inode_lock(src);
 	else
 		btrfs_double_inode_lock(src, dst);
 
+	if (olen == 0) {
+		olen = i_size_read(src) - loff;
+		if (olen == 0)
+			goto out_unlock;
+	}
+	len = olen;
+
 	ret = extent_same_check_offsets(src, loff, &len, olen);
 	if (ret)
 		goto out_unlock;